Low profile electrical connectors are required in a variety of applications, such as in a surface mount electrical connector for connecting an electronic component, such as an IC card, on a planar surface of a printed circuit board. In fact, the outer dimensions of the contacting apparatus in such systems often is not significantly larger than the IC card itself.
With the advent of such apparatus as palmtop computers and pocket-size cellular telephones, there is a constant demand to make the electrical components, including electrical connectors, smaller and lighter in weight. In cellular telephones, for example, there is a constant demand for making smart card connectors, such as SIM-style card readers, as small as possible. Some connector manufacturers simply scale down the dimensions of a conventional connector design to achieve smaller and more dense connectors. However, simply miniaturizing the connectors compromises the connector performance and reliability since smaller dimensions do not always equal the same performance and reliability.
Another, more successful approach to increasing the density of electrical components on a given circuit board and, thereby, reduce the size and weight of the apparatus, is to have all of the components to be true surface mount components. In other words, components that are entirely on one surface of the printed circuit board are used so that the opposite surface of the printed circuit board can be used for mounting other surface mount components. Surface mount connectors, however, have problems or concerns which are separate and distinct from through-hole connectors, such as positioning and coplanarity problems that are not present if the terminals include tail portions or leads which extend through the printed circuit board. One approach to improving the coplanarity of surface mount terminal leads is to increase the resiliency of the leads so that, when the connector is placed on the surface of the printed circuit board, the leads deform to take up any tolerances that allow them to be brought in line, or coplanar, with the other surface mount leads. If an individual surface mount lead is not sufficiently resilient and does not deform to the position of the other leads, some of the surface mount leads will be in contact with the printed circuit board while others will not be in contact with the board.
Surface mount connectors as described above, such as smart card connectors, typically include terminals having resilient contact beams that make contact with the contacts of the IC card or module. It is critical that these cantilevered beams be sufficiently resilient such that all of the contact beams make contact with the IC card contacts. The resiliency of a contact beam typically is determined by a bend in the terminal. The terminals of such connectors also include a surface mount tail which is soldered to circuit traces on the surface of the printed circuit board. Typically, the surface mount tails project from a body or housing of the connector and are formed downwardly to make contact with the surface of the printed circuit board. Therefore, with the solder tails bent downwardly and the cantilevered beams bent upwardly, there often is a trade-off between the resiliency of the surface mount tails and the cantilevered contact beams, because the height or profile of the overall connector apparatus is given or at least extremely limited.
The present invention is directed to solving these problems and particularly solving the dilemma between the resiliency of the surface mount tails and the cantilevered contact beams in order to maximize the resiliency of the terminals without increasing the height or profile of the connector apparatus.